Macrobenthic Community Structure in a Transplanted Eelgrass (Zostera marina) Meadow

Self Cite

Numencal abundance, species composition and size of fish and shrimp were compared among (1) unvegetated, (2) transplanted (3) recently seed-colonized and (4) matule, natural eelgrass habitats to determine the equivalence of transplanted eelgrass beds to their natural counterparts In general, fish and shrimp were most abundant in mature natulal eelgrass habitats and least abundant in unvegetated habitats We developed a vector-graphical analysls that shows eplbenthic faunal abundance to be closely coupled with eelgrass bed development In an area where transplants performed poorly, the faunal component had a different composition and significantly lower numerical abundance In companson to natural beds Fauna1 abundance and composition in a 1 9-yr-old transplanted bed and a 6-mo-old seed-developed bed were indistinguishable from mature natural eelgrass beds Our data Indicate that recruitment of fish and shrimp to eelglass habitats established through transplantahon can occur in time, though not as rapidly as with naturally-seeded beds Area1 shoot density may serve as an inexpensive diagnostic parameter of functional equivalence for most resident macroeplfauna Abundance data need to be interpreted through functional mechanisms such as predation which act to produce the observed abundances in older to separate habitat function from dysfunchon Restored seagrass habitats have the potential to make substantial contributions to fish and shrimp production provided the habitats persist

Section: Discussionmentioning

confidence: 99%

Comparisons of fauna among natural and transplanted eelgrass Zostera marIna meadows: criteria for mitigation

Fonseca¹,

Kenworthy²,

Colby³

et al. 1990

Self Cite

“…Seagrass shoot density is sometimes positively correlated with macrofaunal abundance and thus secondary production (e.g. Homziak et al 1982, Boström & Bonsdorff 2000; but see Boström et al 2006).…”

Section: Discussionmentioning

confidence: 99%

Evaluating estuarine habitats using secondary production as a proxy for food web support

Wong

Peterson

Piehler

2011

The management, restoration, and conservation of estuarine habitats would benefit from knowledge of habitat-specific functions that reflect important ecosystem services. Secondary production may provide a comprehensive metric of food web support because it synthesizes contributions of local primary production, food subsidies from other habitats, and the protective influences of habitat structure. Despite widespread perceptions of how habitats compare in food web contribution, few methodologically comparable studies on secondary production across multiple estuarine habitats exist. At field sites in North Carolina, USA, annual secondary production was estimated for macrobenthic infaunal and epifaunal communities in salt marshes, seagrass meadows, oyster reefs, intertidal and subtidal flats, and on shoreline stabilization structures. Habitats with hard emergent or biogenic structure generally exhibited higher secondary production than habitats lacking structure. Oyster reef had the highest secondary production, ranging from 467.3 to 853.7 g ash free dry mass (AFDM) m −2 yr −1, while shoreline stabilization structures ranked high because of dense epifaunal communities. Estimates of secondary production suggest ranking of natural habitats as oyster reef > salt marsh > seagrass > intertidal flat and subtidal flat. Undesirable impacts of shoreline stabilization structures on adjacent habitats made their inclusion in this ranking of food web support by habitat difficult. The importance of suspension feeders on oyster reefs, shoreline stabilization structures, and in some marshes suggests that secondary production patterns are partly influenced by external subsidies facilitated by support from habitat structure. Consequently, estuarine rehabilitation should include structural habitat elements that will contribute to ecosystem production at higher trophic levels. Without such habitat restoration, the fate of estuaries in the USA affected by anthropogenic stressors may be loss of habitat diversity and prevalence of low-trophic-supporting habitats.

“…These plants represent important physical structures, which provide habitat and nursery areas for many animals ( k k u c h i 1980) and enhance the deposition of particulate material (Fonseca et al 1982, Fonseca & Fisher 1986. Interconnected roots and rhizomes also increase sediment stability (Orth 1977).…”

Section: Introductionmentioning

confidence: 99%

Nitrogen cycling in sediments with estuarine populations of Potamogeton perfoliatus and Zostera marina

Caffrey¹,

Kemp²

1990

131

ABSTRACT. Rates of nitrogen transformations and concentrations of extractable NH,+ and NOs-(plus NO2-) were measured in estuarine sediments vegetated with the submersed macrophytes Potarnogeton perfoliatus and Zostera manna, and in adjacent bare sediments, 3 or 4 times during the growing season. Nitrification and denitrification potentials were measured in substrate-amended sediment slurries at 5 depth intervals to provide a measure of bacterial activity. In general, rates were significantly higher in vegetated compared to bare sediments. It appears that both plant species affected nitrogen transformations through several similar mechanisms, while the microbial community, in turn, regulated nitrogen available for plant growth. In P, perfoliatus beds, ammonification and potential nitrification rates were correlated. Both exhibited summer maxima coinciding with peak plant biomass and productivity. Although vertically integrated (0-12 cm) amrnonification rates were about t w c e as high in vegetated than in bare sediments, NH4+ pools were significantly lower, probably due to high plant nitrogen demand. In contrast, denitrification rates were highest in spring when NO3-concentrations peaked, and were significantly correlated to nitrification rates in both spring and fall. Denitrification was only about 2 0 % of total NO3-reduction, suggesting that NH4+ production from NO3-may b e important in conserving nitrogen within the grassbed. In sediments with Z. marina, rates of ammonification, and nitrification and denitrificabon potentials each exhibited a distinct seasonal cycle, indicating that rates were not as tightly coupled as in P. perfoljatus beds. High amrnonification rates exceeded plant demand leading to NH,' accumulation. Potential nitrification rates were highest in vegetated sediments during fall. Denitrification rates, which were also greater in vegetated than in bare sediments, were highest in spring when NO3-concentrations were high. Potential denitrification rates comprised about 10 "" of total NO3-reduction, indicating that NO,-reduction to NH,+ dominated. The microbial communities responsible for key nitrogen transformations in the sediments were enhanced by both P. perfoliatus and Z. manna ammonificatlon by inputs of organic nitrogen; nitrification by release of O2 by plant roots; and denitnfication by production of NO3-